As confident in the bedroom as in a gunfight, irresistibly attractive, and often deadly, Ian Fleming’s Bond Girls are some of the coolest female characters in fiction and on the big screen. But how did these sultry, seductive and stunning femme fatales come about?

A new book reveals the two real-life women who more than any others inspired 007’s leading ladies – high-society sisters, Ann and Laura Charteris.

The party-loving duo left a trail of emotional chaos in the upper echelons of British society.

Wooed by rich and powerful men who gave them titles, country mansions and sumptuous London homes, they led a life of shameless hedonism – racking up seven marriages between them.

Indeed, one of Ann’s conquests was Fleming himself.

The pair began an affair while she was still married to her second husband, the Conservative politician and press baron 2nd Viscount Rothermere, enjoying wild, adulterous sexual liaisons, before finally marrying in 1952 after her latest divorce.

“Fleming looked set to be an eternal bachelor but he and Ann had a passionate, exhausting, all-consuming affair which led to his first marriage and her third,” says former BBC World Service journalist Christopher Reindorp, author of Never Shaken, Never Stirred.

“The Charteris girls captured his imagination, with Ann becoming the most important figure in his life until his premature death.

“I’m convinced he based his Bond girls on the character of his lover and then wife but he was also fascinated by Ann’s sister Laura.”

Casino Royale, the first of what would become his wildly successful Bond series, was published the following year in 1953.

Reindorp has researched letters written by the two sisters, the Bond author and their friends, to piece together the alchemy behind their relationships.

The socially competitive sisters bagged a total of seven husbands between them, but nothing in their early years suggested they would become such influential society figures.

Ann was born in London on June 13, 1913, the eldest daughter of Captain Guy Charteris and his wife Frances Tennant. Her grandfather was Hugo Charteris, the 11th Earl of Wemyss.

Her sister Laura was born two years later and they had a brother Hugo, who became a novelist. A third sister, Mary Rose, came along in 1919.

As was the style in the latter days of the Edwardian era, the girls were educated by governesses, but Ann was more bookish and spent some time at Cheltenham Ladies College.

Presented to high society as a debutante, Ann married financier Shane O’Neill, 3rd Baron O’Neill, and they had two children, but she couldn’t resist the overtures of press baron Esmond Harmsworth, eventually marrying him after her first husband was killed in action in the Second World War.

Around the same time, she fell for Fleming’s wit and charm, embarking on a secret affair.

The Bond creator became anxious their illicit liaison would be discovered, writing in one letter: “I know how you leave things lying around like a jackdaw and I expect every day that it will be the end.

“I do wish you’d take trouble and not leave my letters among your brassieres and your pants. Do please try. I know perfectly well that you are going to come along one day with a tragic face and say that all is discovered.”

During this period, Fleming was a senior journalist for The Sunday Times, a rival of Harmsworth’s own newspaper empire.

In another letter, there was a definite hint their love-making involved a bit of sado-masochism: “You have made bruises on my arms and shoulders. All this damage will have to be paid for some time.”

Ann then fell pregnant by Fleming while still married but sadly their daughter, Mary, died soon after her birth in 1951.

She formally separated from Harmsworth at the end of that year and began tentatively making a new life with Fleming, who was spending more and more time at Goldeneye, the beachside home in Jamaica he’d built in 1946.

They married in a quiet registry office ceremony on the Caribbean island in March 1952 while she was pregnant with their second child. Waving goodbye to his life as a bachelor, Fleming was overjoyed with his new status as husband and soon-to-be father but realised he would need a great deal more money to give his bride the sort of life she had become accustomed to, even though her second divorce involved a £100,000 settlement.

“Ann never had to think about money during her years with Esmond and Ian only had his income as a journalist,” Reindorp explains. “He had to get an extra income because he was really worried about supporting Ann. She sort of baited him about starting to write a book by saying, ‘I don’t think you’ll be anything more than a journalist’.

“He wanted to prove to her he could write a book. She was definitely there at the birth of the character James Bond. She gave him the impetus to write.”

Reindorp is convinced Fleming modelled the idea of the Bond girl on his wife and her sister Laura because there are so many similarities between the two women and the Bond girls of the original novels. “Ann and Laura were incredibly glamorous figures on the social scene, wonderful hostesses, and they cared a lot about fashion,” he adds.

“In the novels, Ian took a lot of time describing what the women were wearing. Ian once said the perfect woman was a lady who could make bearnaise sauce as well as she could make love. That was very much Ann.

“She was an accomplished hostess, excellent cook and, with a quite prolific record of extra-marital affairs, I think it’s safe to assume she was equally accomplished in the bedroom. In the society world, both Ann and Laura were known for their magnetic sexuality.”

Reindorp says the sisters also had a certain steeliness about them, very much like Vesper Lynd, the double-agent character from his debut novel Casino Royale, played by Ursula Andress in the 1967 film parody and by French actress Eva Green in the 2006 Daniel Craig remake.

“Vesper was very icy, but very glamorous,” Reindorp adds.

“She was tough and so was Ann, as Ian later found out.”

When the Flemings’ son Caspar was born in 1952, the novelist’s life changed dramatically. In his mid-40s, he was unused to domestic routines.

“The marriage was idyllic in the beginning,” says Reindorp. “They moved into a flat in Cheyne Walk, Chelsea. Laura described it as the happiest of households but Ann’s niece told me that the Flemings were much better at courtship than they were at marriage.

“They went on to have huge rows. There were certainly times when the marriage was at breaking point.

“I felt exhausted just reading letters which showed the strains the marriage was under. There was intense love, but neither of them could resist having affairs.

“In the beginning both turned a blind eye to what was going on. That was the way they did it in society circles.

“There were also strains in the marriage because Ann was keen to buy and develop large properties whereas Ian preferred smaller places.”

After less than a year in Cheyne Walk, Ann and Ian bought a townhouse near Buckingham Palace, which she spent months renovating while her husband complained about the rising costs.

During the winters, Ian would regularly head off alone to Jamaica where he found the peace he needed to write his books and also time to have an affair with a local woman, Blanche Blackwell.

Reindorp believes Caspar was “very damaged by the ups and downs in his parents’ marriage”. During his early years he spent a lot of time with his nanny.

Ann, meanwhile, became fascinated with the rising star of the Labour party at the time, Hugh Gaitskell.

Although he was also married, they began an affair and she was very upset when he died in 1963.

There was further trauma for Ann the following year when Fleming, whom she still loved, died of a heart attack aged just 56, on the day of Caspar’s 12th birthday.

In search of solace, Ann turned to alcohol.

She was further troubled by the mental deterioration of her son who, at 16, was expelled from Eton when a loaded revolver was found in his room.

During a visit to Goldeneye, Caspar swam far out to sea in an apparent suicide attempt, later dying of a drugs overdose at his mother’s London home in 1975. While Ann was leading her whirlwind of a life, Laura was keeping the society columnists busy with her own complex relationships.

She married Walter Long, 2nd Viscount Long, in 1933, and had her only child, Antoinette. Ten years later she married William Ward, 3rd Earl of Dudley, but divorced in 1954.

In 1960 she married Michael Canfield, who was rumoured to be the illegitimate son of Prince George, Duke of Kent.

Her fourth and last husband was John Spencer-Churchill, 10th Duke of Marlborough, but their marriage in 1972 lasted only six weeks before he died and she had to leave the magnificent Blenheim Palace stately home.

Ann died in 1981, aged 68, at Sevenhampton Place, the country home in Wiltshire she had insisted on buying back in the 1950s to give them a grand country mansion for weekend entertaining. Together with Ian and Caspar, she had spent many happy days there before darker times descended.

The three of them rest together at the church of St James in Sevenhampton, at peace after tumultuous lives which might have come straight from the pages of a spy thriller.

• Never Shaken, Never Stirred: The Story of Ann Fleming and Laura, Duchess of Marlborough by Christopher Reindorp (The History Press, £22.99) is published on February 23. For free UK P&P, visit expressbookshop.com or call 020 3176 3832